Coadsorption of Hazardous Substances As(V) and Sb(V) Using Sludge from Acid Mine Drainage

The treatment of acid mine drainage (AMD) with carbonate rocks generates AMD sludge (AMDS), rich in iron oxyhydroxides which shows potential as an adsorption material. This study investigates the adsorption behaviors of arsenic [As(V)] and antimony [Sb(V)] by AMDS. Characterized by X-ray diffraction analysis, AMDS contains high percentage (26.19%) of iron (Fe), i.e., α-FeOOH and γ-FeOOH. Using this AMDS, the coadsorption of As(V) and Sb(V) by AMDS was best described by a first-order kinetic model with the maximum adsorption capacities (MAC) for As(V) and Sb(V) of 20.23 mg/L and 6.784 mg/g, respectively. The study identified a higher affinity for As(V) due to AMDS’s unique mineral composition and surface functional groups like-COOH, -Fe-OH, and -Fe-O-Fe. Acidic environments enhanced adsorption, with mechanisms involving electrostatic attraction and specific adsorption. AMDS is highlighted as a cost-effective and sustainable alternative to synthetic adsorbents, promoting waste management by repurposing AMD byproducts. Future research should validate these findings in real-world scenarios, exploring long-term stability, reusability, and the influence of competing ions.